A snowmobile of conventional construction has a moving track, powered by an engine, which propels the snowmobile forward. Two skis operatively attached to the steering mechanism, operated by the rider, are situated in front of the track to keep the as the rider desires.
A conventional snowmobile ski is constructed of metal and attaches to the steering mechanism at approximately its midpoint. The ski has an upwardly curved forward portion for encountering obstacles and uneven terrain. A stiff loop, usually constructed of a metal rod, is attached to the top of the front end of the ski and is bent upwardly and then backwardly to attach to the top of the ski just to the rear of the point where the ski begins its upward curvature. Some loops attach somewhat forwardly of this point. The loop was originally designed to increase safety in snowmobile use by prevention of the forward portion of the ski from stabbing a person or object during forward movement. It also increases durability of the forward curved portion of the ski and is a convenient handle for moving the snowmobile, especially when the snowmobile is stuck in a snowdrift or the like. The loop is also useful for handling the ski when it is unattached to the snowmobile.
The loop acts as a continuation of the curvature of the forward portion of the ski and thus enhances its ability to handle bumps, or moguls, and obstacles such as sudden changes in terrain. The loop is generally attached to the ski by welding. Most skis also have bridges or bars running along their length for stability and strength.
This type of ski has been the standard for many years, but recently a new ski has been developed that is not constructed of metal but of flexible and resilient plastic. The newer ski is usually wider than the standard metal ski and also lighter. One of the disadvantages of the metal ski that the new plastic ski is designed to prevent is the damage to the ski and jarring of the rider from the encountering of unyielding obstacles during forward movement. A snowmobile with conventional metal skis attached accommodates bumps, moguls, washboard patterns, and trail ruts in that its curved forward portion, and for large bumps its loop, enables the ski to rise up and over the bump and continue on its way. The curved forward portion and loop are also helpful when encountering unexpected obstacles such as concealed rocks or logs.
Snowmobiles are very heavy relative to the surface areas of their skis and often travel at great velocities, such that when the ski hits a mogul or other obstacle it does so with great force, notwithstanding the curvature of its forward portion, and often suffers bending or other structural damage. The loop and bridges are designed in part to avoid such damage, but the ski is often considerably damaged nonetheless through sustained aggressive use. At the same time, the unyielding nature of the ski forces the rider to endure a bumpy and uncomfortable ride, though shock absorbers mitigate the situation somewhat.
The newer ski is made of plastic which, unlike metal, yields and flexes and thus better endures the shock of hitting bumps and ruts, both in terms of a smoother ride for the rider and less damage to the ski from bending and the like because the ski is able to momentarily deform to absorb the impact and spring to its original position owing to its flexibility and resiliency. Generally, some parts of the ski continue to be made of metal or similarly stiff material as required by their function, such as bolts and the like and the attachment piece of the ski to the snowmobile.
The plastic ski has a loop much like the metal ski except that in the former the forward part of the loop is attached to the bottom of the frontal portion of the ski and often extends beneath it a certain distance. The loop, as in the metal ski, curves upwardly and then rearwardly to an attachment point located approximately where the frontal curvature of the ski begins. The loop generally is constructed of the same type of plastic as the rest of the ski and is attached thereto by bolts or equivalent attachment means. Since the loop as well as the ski is constructed of flexible material, it allows the frontal curvature of the ski to flex slightly when encountering bumps, further enhancing the ski's ability to absorb the impact.
Other types of skis include one constructed of aluminum with a plastic skin disposed on its bottom for better performance.
Notwithstanding the improvements in the performance of the plastic ski over the metal ski, the snowmobile and rider still experience considerable jarring and damage from obstacles, especially during sustained rides at high velocity in rough terrain. Additionally, the high curvature required of the forward part of the ski, though it assists in handling obstacles, increases wind resistance and can interfere with handling of the snowmobile in close quarters. Most importantly, the high curvature limits the amount of ski material involved in the flexible motion of the forward part of the ski, lessening the shock absorbing characteristics.